A photosensitive material capable of easily and rapidly obtaining images by a developing process comprising a dry process using heat, i.e., a heat-processable photosensitive material, has been usually known. Such heat-processable photosensitive materials and the image forming processes thereof are described in, for example, Japanese Patent Examined Publication Nos. 43-4921 (1968) and 43-4924 (1968); The Fundamentals of Photographic Engineering, pp. 553-555, Corona Publishing Co., 1979; Research Disclosure, RD-17029, pp.9-15, June, 1978; and so forth.
In recent years, there have been some attempts to research and develop heat-processable color photosensitive materials in which color images are obtained by making selective use of various types of dye-donors. Among these attempts, there is a system for obtaining color images in such a manner that a diffusible dye is released or formed in a heat developing process and is then transferred. This system is excellent in stability and sharpness of images as well as in easiness and rapidness of processing operations. These dye-transfer type heat-processable color photosensitive materials and the image forming processes thereof are described in, for example, Japanese Patent Publication Open to Public Inspection (hereinafter called Japanese Patent O.P.I. Publication) Nos. 59-12431 (1984), 59-159159 (1984), 59-181345 (1984), 59-229556 (1984), 60-2950 (1985), 61-52643 (1986), 61-61158 (1986), 61-61157 (1986), 59-180550 (1984), 61-132952 (1986) and 61-139842 (1986); U.S. Pat. Nos. 4,595,652, 4,590,154 and 4,584,267; and so forth.
Besides the above, there are heat-processable photosensitive materials which use a coupler capable of forming a non-diffusible dye, such as those described in, for example, Japanese Patent O.P.I. Publication Nos. 62-44737 (1987), 62-129852 (1987) and 62-169158 (1987); and heat-processable photosensitive materials which use a coupler capable of forming a diffusible dye, such as those described in, for example, U.S. Pat. Nos. 4,631,251, 4,650,748, 4,656,124 and so forth. These photosensitive materials are excellent in that color images having a higher density and lower fogging can readily be obtained.
However, these heat-processable color photosensitive materials still have the problems remaining unsolved, such as not so satisfactorily lowered fogging, color mixed up by interlayer transfer of the oxidized products of a reducing agent, or seriously produced stains.
For the purpose of solving these problems, the compounds capable of capturing the useless oxidized products of a reducing agent, such as the couplers or the reducing agents described in, for example, Japanese Patent O.P.I. Publication Nos. 60-119555 (1985), 60-133449 (1985), 60-198540 (1985) and 60-230652(1985), each of which has already been known. The compounds described in these patent applications still have the problems; the oxidized products of a reducing agent are not satisfactorily captured, fogging is not satisfactorily lowered, and color mixing or fogging is produced by transfer of the colored compounds reacted with the oxidized products of a reducing agent: and besides the above problems, they have another problem that a maximum density as well as fogging is lowered to a large extent.